Process for producing shaped articles of crystalline polyolefins having a roughened surface

ABSTRACT

SHAPED ARTICLES SUCH AS FILM, SHEET, TAPE OR FILAMENTS, OF CRYSTALINES POLYOLEFIN RESINS SUCH AS POLYPROPYLENE OR ETHYLENE, HAVING A UNIFORMLY AND REMARKABLY ROUGHENED SURFACE, AND USEFUL FOR THE PRODUCTION OF SYNTHETIC, PAPER, SYNTHETIC, PULP, STRING, WOVEN FABRIC, KNITTED PRODUCTS, ETC., CAN BE PREPARED BY COOLING AND SOLIDIFYING A CRYSTALLINE POLYOLEFIN RESIN EXTRUDED FROM A DIE WHICH IS IN A MOLTEN BUT PREFORMED STATE, BY CONTACTING WITH A SPECIFIED SOLVENT   HAVING A BOILING POINT OF 30*-400*C. AND MAINTAINED AT A TEMPERATURE WHICH IS IN THE RANGE OF 0*-100:C. AND LOWER THAN SAID BOILING POINT AND DOES NOT DISSOLVE SAID CRYSTALINE POLYOLEFIN RESIN, WHICH SOLVENT IS USED ALONE FOR COOLING OR IN THE FORM FLOATING ANOTHER COOLING LIQUID.

July 2, 1974 HIROSH! HARUTA ETAL 3,822,333

PROCESS FOR PRODUCING SHAPED ARTICLES OF CRYSTALLINE POLYOLEFINS HAVINGA ROUGHENED SURFACE Filed July 31, 1972 4 FIG.I

United States Patent Claims priority, application Japan, Apr. 2, 1969,44/25 311 Int. Cl. 1329c 25/00 US. Cl. 264-179 7 Claims ABSTRACT OF THEDISCLOSURE Shaped articles such as film, sheet, tape or filaments, ofcrystalline polyolefin resins such as polypropylene or polyethylene,having auniformly and remarkably roughened surface, and useful for theproduction of synthetic paper, synthetic pulp, string, woven fabric,knitted products, etc., can be prepared by cooling and solidifying acrystalline polyolefin resin extruded from a die which is in a moltenbut preformed state, by contacting with a specified solvent having aboiling point of 30400 C. and maintained at a temperature which is inthe range of 0l00 C. and lower than said boiling point and does notdissolve said crystalline polyolefin resin, which solvent is used alonefor cooling or in the form floating upon another cooling liquid.

RELATED APPLICATION This application is a continuation-in-part of Ser.No. 22,380 filed on May 24, 1970, now abandoned.

DESCRIPTION OF THE INVENTION The present invention relates to a processfor producing shaped articles of crystalline polyolefin resins havingroughened surface. More particularly, it relates to a process forproducing shaped articles such as film, sheet, tape or filaments, whichcomprises cooling and solidifying a crystalline polyolefin resinextruded from a die and being in a molten but preformed state, incontact with a specified solvent.

Crystalline polyolefins, for example, polypropylene, polyethylene,propylene-ethylene copolymer, poly-4 methylpentene-l, polybutene-l, havefound a large variety of applications in the manufacture of shapedarticles such as films, sheets, tubes, tapes, filaments and the like.The surfaces of these shaped articles are generally smooth, lustrous andsuperior to those of other polymers in ap pearance but they are notsuitable for writing with a pen, and have poor printability and pooradhesiveness.

Heretofore, many processes for making coarse the surfaces of shapedarticles of crystalline polyolefins have been proposed. For example,there are known embossing process, sand blasting process, chemicaletching process, solvent treating process, foaming process,pigment-mixing process and the like. In the case of shaped articles suchas sheets or films, an embossing process is carried out by a chill rollhaving coarse surface or an embossing roll. This process cannot becarried out without special apparatuses such as embossing rolls orpattern rolls. Further a method which makes coarse the surface of shapedarticles by admixing a foaming agent into a material to be shaped tofoam at the time of shaping is not preferable because it gives a certainkind of change not only upon the surface of shaped articles but also tothe constructional properties of shaped articles themselves. On theother hand, such treating methods as sand blasting, chemical etching andsolvent treating have been heretofore carried out in addi- 3,822,333.Patented July 2, 1974 tional steps after once shaped articles ofpolyolefins are manufactured. However, they have defects in that theyneed a complicated and prolonged processing step, and also theiroperational efficiency is generally poor. Among the above-mentionedprocesses, the solvent-treatment has not been easy to carry out,because, when crystalline polyolefin resins are used, there has been nosolvent capable of dissolving them at low temperatures. Namely, anysolvent has no appreciable dissolving power for crystalline polyolefinresins at room temperature; above 60 C., a certain kind of solvent comesto exhibit a partially dissolving power; and in order to exhibit acompletely dissolving power, a higher temperature is necessary.

Accordingly, in the treatment of the surface of shaped articles ofpolyolefin resins with a solvent, it is a conventional process toimmerse said shaped articles in a solvent heated to a suitabletemperature capable of dissolving said resins, for a suitable period oftime, to dissolve the surface portion of the shaped articles havingreached the temperature capable of dissolving said portion, followed bytaking out and cooling the articles, and removing a remaining portion ofthe solvent. Further, in order to improve effectiveness attained by thetreatment and to shorten the time necessary for the treatment, shapedarticles are often treated with a heated solvent after preheated to atemperature in the range where the shaped articles are not thermallydeformed. However, if these processes are applied to sheets or filmshaving a thickness of 1 mm. or less, or tapes or filaments having a sizeof 1 mm. or less, the temperature of solvent as well as the preheatingtemperature of resin cannot be raised over the melting temperature ofthe resin in order to avoid the risk of deformation of the shapedarticles. Accordingly, in order to obtain sufiicient surface-rougheningeffectiveness, a treating time of at least several seconds, usuallyseveral minutes, is necessary even at a temperature close to the meltingpoint, and further a treating time of at least one minute, usuallyseveral ten minutes, is necessary at a temperature lower than C. Forexample, Tessandori et a1. (U.S. Pat. 3,179,484) have proposed a processof treatment for at least one minute with a solvent having a temperaturelower than 100 C. The effectiveness of this process consists in thatdyed articles having a good dye receptivity and a large color fastnesscan be obtained in the successive dyeing step. Accordingly, in thiscase, surface-roughening does not seem to be attained in spite of such along treating period of time as at least one minute, even though theshaped articles may be swollen. Further, there is no descriptionrelative to the surface-roughening in the reference. In fact, as shownin the Comparative Examples described below, no outstandingsurface-roughening effectiveness as in the present invention can beattained according to Tessandori et al.s process. As mentioned above,there has never been disclosed a process in which the surface-rougheningof crystalline polyolefin resins can be attained within a very shorttime of less than several seconds, by the use of a solvent which isincapable of dissolving once solidified crystalline polyolefin resins ata temperature lower than 100 C. under the atmospheric pressure, at saidtemperature.

The first object of the present invention is to provide a uniformly andremarkably surface-roughened shaped article of crystalline polyolefinresins having fine rises and falls on the surface.

The second object of the present invention is to provide a method inwhich no apparatus is necessary for a posttreatment which is usuallyused for a melt-extrusion shaping and requires a long retention time,thereby to make the whole treatment cost inexpensive.

The third object of the present invention is to provide a method forpreventing the thermal deformation of shaped articles during the heatingstep which is liable to occur in the case of post-treatment and alsoparticularly in thinner products.

Other objects will be clarified by the following description.

The above-mentioned objects can be attained by the method of the presentinventors.

According to the method of the present invention, the surface of shapedarticles can be remarkably roughened just after the melt-extrusionshaping of crystalline polyolefin resins, by cooling and solidifyingsaid resins in a molten but preformed state, by contacting with aspecified solvent having an affinity with said resins in the molten butpreformed state, but not dissolving said resins cooled to a temperaturein a specified range at which the solvent is maintained, by the contactwith the solvent.

It is surprising enough that there is a great difference in thesm'face-roughening effectiveness between a shaped article preheated to atemperature below the melting point of said resins and treated with asolvent, and a shaped article obtained by extruding said resins from adie and treating the resulting resins in a molten but preformed state,with a solvent. Namely, as shown in the Examples and ComparativeExamples described below, a remarkable surface-rowghening can beattained from resins in a molten state, but such an efiect cannot beattained from a shaped article preheated to a temperature below themelting points of said resins.

Further surprisingly, the surface-roughening treatment in a molten statecan be completed within a very short time of at most several secondsnecessary for cooling and solidifying the surface of a shaped article inthe cooling step of melt-extrusion shaping. Moreover, thesurfaceroughening treatment in a molten state becomes feasible only bycombining with the cooling step, because the resulting roughened surfaceobtained in a molten state is set only by cooling.

The present invention resorts to a process for producing shaped articlessuch as film, sheet, tape or filaments of crystalline polyolefin resinshaving a thickness of 1 mm. or less and a roughened surface, whichcomprises cooling and solidifying a crystalline polyolefin resinmeltextruded from a die and being in a molten but preformed state, bycontacting with a solvent selected from the group consisting ofaliphatic, aromatic, alicyclic or halogenated hydrocarbons, heterocycliccompounds and esters of aliphatic alcohols and aliphatic or aromaticcarboxylic acids, each having a boiling point of 30400 C., andmaintained at a temperature which is in the range of -100 C. and lowerthan said boiling point, and at which said crystalline polyolefin resinis not dissolved, which solvent is used alone for cooling or in the formtlloating upon another cooling liquid.

According to the present invention, a shaped article of crystallinepolyolefins having a uniformly and remarkably roughened surface can bereadily prepared. Further, since cooling and solidification are carriedout simultaneously with solvent-treatment in the present invention, theapparatus and time for the processing of post-treatment can be saved ascompared with the conventional solvent-treatment carried out aftershaping and solidification, and hence an economical advantage can bethereby obtained. Furthermore, there is no fear of thermal deformationwhich is liable to occur in the heating step of post-treatment and alsoparticularly in the case of thinner shaped articles. Still further, theadjustment of treatment strength is easier than in the case ofpost-treatment. Further, surprisingly, even a solvent, such as n-hexane,n-heptane, or the like, which is incapable of dissolving once solidifiedcrystalline polyolefins such as some polypropylenes and some highdensity polyethylenes at a temperature lower than the boiling point ofthe solvent under the atmospheric pressure, can exhibit a suflicientsurface-toughening performance according to the process of the presentinvention.

Further, according to the process of the present invention, when themolten resin is cooled and solidified, both the dissolution of itssurface portion into a solvent and the precipitation of the dissolvedresin due to the successive cooling, are completed within an extremelyshort time, that is, almost instantaneously, and hence there 15 no timefor the dissolved resin enough to 'be dispersed out of the surface ofthe shaped article and the almost all portion of the dissolved resin areprecipitated and deposited onto the surface of the shaped article.Accordmgly, there is no loss of the resin and a very good efficiency isbrought about.

The above-mentioned effectivenesses of the present 1nvention can beattained by cooling and solidifying a crystalline polyolefin resin in amolten state, extruded from a die, while contacting it with a solvent,in a cooling liquid. Concretely, the resin in a molten state, extrudedfrom a die is cooled and solidified by being put into a solvent vesselor a vessel of a cooling liquid floating a solvent on its surface.

The solvents to be used in the present invention are aliphatic,aromatic, alicyclic or halogenated hydrocarbons, heterocyclic compoundsor esters of aliphatic alcohols and aliphatic or aromatic carboxylicacids. Among them, it is preferable to use aliphatic or alicyclichydrocarbons having a boiling point of 30100 0., because, in the case ofsolvents having lower boiling points, the removal of solvent after thetreatment is more readily carried out, for example, by evaporation, andfurther, when the treatment is carried out at a temperature which is inthe above-mentioned ranges and at which the resins are not dissolved,more uniform and finer surface-roughening treatment becomes possible.

Concretely, there are illustrated as aliphatic hydrocarbons, pentane,hexane, heptane, octane, nonane, decane, gasoline, petroleum ether,petroleum benzine, ligroin, kerosene, gas oil, liquid paraflin, etc.; asaromatic hydrocarbons, benzene, toluene, xylene, etc.; as alicyclichydrocarbons, cyclopentane, cyclohexane, methylcyclohexane,cycloheptane, decahydronaphthalene, tetrahydronaphthalene, etc.; ashalogenated hydrocarbons, monochloropropane, monochlorobutane,monochloropentane, trichloroethane, tetrachloroethane,trichloroethylene, tetrachloroethylene, etc.; as heterocyclic compounds,tetrahydrofuran, etc.; and as said esters, propyl acetate, butylacetate, amyl acetate, dioctyl adipate, dioctyl sebacate, dioctylphthalate, etc. Solvents having a boiling point lower than 30 C. are noteconomical, because they must be used in the treatment, in a statecooled to a particularly low temperature, due to their large volatility.The abovementioned solvents can 'be used also as a mixture with eachother or with a diluent therefor. By these means, the extent ofsurface-roughening of the shaped article of the present invention can becontrolled.

Solvents in a solvent vessel or solvents floating on a cooling liquid,in the present invention, as mentioned above, must be maintained at atemperature which is in the range of 0-100 C. and lower than the boilingpoint of the solvents and at which the shaped article of the polyolefinresins is not dissolved. If the temperature of solvent exceeds C., anexcessive treatment or an excessive dissolution of resin occurs. On theother hand, if the temperature is lower than 0 C., treatment isinsufiicient.

As for crystalline polypropylene, it is preferable that the temperatureof solvent is in the range of 0-70 C., while, as for high densitypolyethylene, it is preferable that the temperature is in the range of0-60 C. In these ranges, the resins are not dissolved, and more uniformand fine surface-toughening is possible.

The temperature at which the above-mentioned resins become soluble orare dissolved, means the lowest temperature at which the resins in theform of small pieces are dissolved by maintaining them at a constanttemperature for 10 minutes with stirring in such a solvent as gives aratio of solvent to polymer of about 100:1.

Since crystalline polyolefin resins contain usually a small amount ofnon-crystalline portion, this portion may be extracted by theabove-mentioned solvents even when the crystalline portion as maincomponent is not dissolved. However, if the amount of such an extractedportion is less than by weight, the present invention can be effectivelycarried out.

The temperature at which the resins are dissolved in the solvents,varies depending upon the combination of the resins and the solvents,but, generally, if a temperature used is lower than the following, theresins will not be dissolved in the solvents of the present invention:

Crystalline polypropylene 70 C. High density polyethylene 60 C. Lowdensity polyethylene 40 C. Medium density polyethylene When a vessel ofa cooling liquid floating a solvent thereon is used in the presentinvention, the cooling liquid must be the one having a specific gravitygreater than that of the solvent and also capable of forming a separatephase from that of the solvent, and maintained at a temperature equal toor lower than that of the solvent. The difference between the specificgravity of the solvent and that of the cooling liquid, is preferable tobe more than 0.1, in order to prevent a disturbance in the form ofdroplets, along the boundary between the solvent and the cooling liquid.Whether or not the solvent and the cooling liquid form separate phasesfrom each other, can be judged by introducing the both into a vessel,stirring and allowing them to stand.

As for the cooling liquid, water, aqueous solutions of inorganicsubstances, mercury, liquids of organic substances, etc. can be used.Among them, water and aqueous solutions are particularly preferablesince they have a large cooling capacity and are economical. If thespecific gravity of the solvent is close to that of water, thedifference in specific gravity can be made larger by using aqueoussolutions of inorganic substances or the like.

The advantages of using a vessel of a cooling liquid floating a solventlayer thereon, in the present invention, are as follows: the retentiontime of the resin in the sol vent can be shortened thereby to reduce anundesirable swelling of the shaped article with the solvent; the amountof the solvent to be used is small; if a cooling liquid having a largecooling capacity such as water is used, the amount of the solventevaporated in the treatment is small; and the extent of treatment can beadjusted by varying the thickness of the solvent layer. The thickness ofthe solvent layer floated on the cooling liquid is preferable to be morethan 0.5 mm., in order to obtain a sufiicient surface-rougheningeffectiveness. The solvent should be supplied as it is consumed.

In the present invention, the strength of treatment or the depth of theroughened surface-layer formed by the treatment can be adjusted byvarying the temperature of the solvent. The higher the temperature, therougher and the deeper the treated layer. In addition, when a vessel ofa cooling liquid floating a solvent thereon is used in the presentinvention, the solvent is attached onto the surface of the resin in theform of film and pulled into the cooling liquid since the solvent has agreat aflinity for the resin. Thus, the contact of the solvent with theresin is maintained also in the cooling liquid. Accordingly, the higherthe temperature of the cooling liquid which decides the temperature ofthe accompanying solvent, the stronger the extent of treatment.

The temperature of the solvent or the cooling liquid in the presentinvention can be readily controlled by wellknown cooling or heatingmeans. Particularly when a solvent having a low boiling point is used,it is preferable to use the solvent or the cooling liquid sufiicientlycooled, in order to prevent its evaporation. If the boiling point of thesolvent is lower than the temperature of the molten resin, it ispreferable to seal the vessel, in order to prevent the solvent vaporfrom escaping. Sealing is carried out using an inert gas such asnitrogen, for safety and in order to avoid the loss of solvent. In sucha case, even when the pressure is altered to either slightly greater orsmaller than the atmospheric one, the gist of the present invention isnot altered thereby.

The time necessary for the surface of the resin in a molten state to becooled and solidified, is very short as in the general case where theresin is cooled by water, that is, several tenth second or at mostseveral seconds. The surface-toughening of the present invention iseffected within such a short period of time. The resulting roughenedsurface is fixed along with the cooling and solidification of thesurface, and not dissolved away at the time of subsequent cooling of thepolyolefin resin in the solvent. The cooling of the entire shapedarticle is also usually completed in one minute or less when the articlehas a thickness of 1 mm. or less; and in about /2 second when it has athickness of about 0.03 mm.

The method of the present invention can be applied for delustering,surface-roughening, capacity-making of shaped articles for the purposeof beautification or variation of the product. Further, it can also beapplied for the improvements in Writability, printability, dyeability oradhesiveness.

As for the shaped articles to which the present invention can beapplied, sheet, film, tape and filaments can be illustrated. Further itcan be applied to the articles requiring uniaxial or biaxial stretching.

The shaped articles prepared according to the process of the presentinvention are suitable for producing synthetic paper, synthetic pulp,string, woven fabrics, knitted products by utilizing the properties ofcrystalline polyolefins, particularly, crystalline polypropylene andhigh density polyethylene, having superior rigidity, strength, hardness,stretchability, etc. A coating capable of affording adhesiveness orprintability can be applied to the surface. Further, a press roll or aheating roll can be used in order to control the roughness of thesurface layer of the resin or to increase the strength thereof.

It is possible to add additives such as stabilizers, antistatic agents,adhesion-, printabilityor dyeability-improving agents, pigments or thelike and fillers such as reinforc ing agents, extenders, to thecrystalline polyolefin resins to be used in the present invention.

The effectiveness of the treatment of the present invention can bepromoted by adding pigments or fillers to the resin. Namely, theiraddition makes the structure of the surface finer and more rigid.

Further, in the present invention, the above mentioned additives can bealso added to the solvent, not to the crystalline polyolefin resins.Further, in the present invention, a solution obtained by dissolving inthe solvent of the pres ent invention, a resin other than thecrystalline polyolefin resins to be surface-treated, for example, thosecapable of making the surface of the crystalline polyolefin resin,sticky; a suspension obtained by suspensing in the solvent of thepresent invention, a resin; or an inorganic compound in a finely dividedstate, for example, those capable of increasing the roughness of thesurface of the crystallilne polyolefin resins, can be used in place ofthe solvent a one.

The solvent remaining on the surface of the shaped articles aftercompleting the treatment, cooling and so1idification according to thepresent invention, can be removed by any drying means such as a hot air,when a solvent having a high volatility is used and by washing withanother volatile solvent followed by drying when a less volatile solventis used.

In order that the invention may be well understood, the followingexamples are given by way of illustration only.

EXAMPLE 1 An experiment was carried out using an apparatus as shown inFIG. 1 of the accompanying drawings.

The numerals shown in FIG. 1 refer to the following matters:

An isotactic polypropylene having an intrinsic viscosity of 1.40 asmeasured in Tetralin at 135 C. and an isotactic index (extractionresidue after 10 hrs. reflux in n-heptane) of 96% was melt-extruded froma circular die 1 at 220 C. using a usual extruder, into a molten tube 2,which was then expanded by air supplied through an airinlet pipe 14.n-Hexane 3 as a solvent at 20 C. was continuously fed through asolvent-feeding pipe 8, which solvent was floated on cooling water 4 at20 C., while maintaining a thickness of layer of 3 mm., the surface ofthe solvent being located 100 mm. below the lower end of the die lip.The cooling water 4 was also continuously fed through a coolingwater-feeding pipe 9. The expanded film was introduced into the insideof a cooling cylinder 6 having a length of 150 mm. whose inner wallsurface was wetted by allowing the cooling liquid floating the solventthereupon to overflow from its upper edge, whereby the film was cooledand solidified by the contact with the wetted inner surface. Theresulting treated tubular film 12 was flattened by a guiding plate 10and pinch rolls 11 and taken up at a take-up speed of m./min. to give alaid-flat film 13. The n-hexane remaining on the surface of film wasremoved by evaporation by blowing a hot air at 60 C. Thus, asurface-roughened film designated as Sample No. l was obtained. Thevapor of solvent formed by the contact with a high temperature moltenresin and occupying the space 15 filled with nitrogen gas is preventedfrom escaping to the outside by means of a sealing cover 7 and a sealingwater 5.

The above-mentioned procedure was repeated except that only water wasused for cooling (without using nhexane) to give Sample No. 2. Noroughened surface was obtained in the case of Sample No. 2. Theproperties of films of No. 1 and No. 2 are shown in the following Table.

Thlck- Lustre Percent- Appearance ness (perage transof Sample Surfacecent) mission surface Inner 92 Smooth. 1 11o{ 2.7 {g t fi moo 2 i 110}83 {Smooth Sample No. 1 had an outer surface remarkably roughenedaccording to the treatment of the present invention. It was a mat filmhaving an opaque, white and paper-like appearance. On the other hand,No. 2 was a transparent lustrous film.

EXAMPLE 2 film by n-hexane. The n-hexane attached was then evaporated byblowing a hot air at 60 C. to give a surfaceroughened film (Sample No.3).

The above-mentioned procedure was repeated except that only water wasused for cooling (without using liquid paraflin) to give Sample No. 4.Both of the Sample Nos. 3 and 4 had a thickness of about 30p. No. 4 wastransparent and lustrous, whereas No. 3 according to the presentinvention was white and opaque and had a mat and paper-like appearance.

Lustre of outer Percent- Sample surface age trans- N 0. (percent)mission EXAMPLE 3 An experiment was carried out using an apparatus asshown in FIG. 2.

The numerals shown in FIG. 2 refer to the following matters:

circular die molten tube solvent cooling water sealing water sealingcover solvent feeding pipe cooling water-feeding pipe pinch rolllaid-flat tube air-inlet pipe cooling water-discharging pipe guide rollcooling water vessel solvent-separating plate An isotactic polypropylenehaving an intrinsic viscosity of 1.40 and an isotactic index of 96% wasmelt-extruded from a circular die 1 at 220 C. using a usual extruder,into a tubular film, which was then expanded by air supplied through anair-inlet pipe 14. n-Heptane 3 as a solvent at 20 C. was continuouslyfed through a solvent-feeding pipe 8, which solvent was floated oncooling water 4 at 20 C., while maintaining a thickness of 3 mm. in theform of layer, the surface of the solvent being located 100 mm. belowthe lower end of the die lip. The cooling water 4 was also continuouslyfed through a cooling water-feeding pipe 9. The expanded film was cooledand solidified by introducing it into the cooling water floating thesolvent thereupon. The film thus solidified was flattened by means ofpinch rolls 11 having a nip line at a distance of 300 mm. from thesurface of the solvent, and taken up as a laid-flat film 13 at a take-upspeed of 5 m./min. through a guide roll 17. In this case, the coolingwater inside and outside the film is circulated by means of a coolingwater-feeding pipe 9 and a cooling water-discharging pipe 16 to maintaina constant temperature. Further, n-heptane 3 inside and outside the filmis continuously fed through a solventfeeding pipe 8 so as to maintain aconstant thickness of the layer, since a small amount of solvent is lostby accompanying the film. The tubular film thus obtained was cut open,and n-heptane remaining on the surface of film, was removed byevaporation by blowing hot air to give Sample No. 5 having roughenedsurfaces.

The above-mentioned procedure was repeated except that toluene wassubstituted for n-heptane to give Sample No. 6. Further, Sample No. 7was similarly obtained without using any solvent. As shown in thefollowing Table, Sample Nos: 5 and '6 prepared according to the presentinvention were white and opaque and both had a paperlike and matappearance on both the surfaces, whereas Sample No. 7 as a control waslustrous and transparent.

surfaces.

Thlck- Lustre Percent- Sample ness (perage trans- No. (a) Surface cent)mission Appearance Inn 13 Rouiglticned surface, er.-. w 1 e, opaque 120{Outer 11 pager-like.

o. I 10 Rouhgiltiened surface, M nner-.. w e opa ue 6 120 {Outer 8palg'er like.

0. Flat and smooth 7 g 100 {Inner 116 surface, non-color,

""" Outer-.- 112 transparent.

EXAMPLE 4 This Example was carried out using an apparatus as shown inFIG. 3. The numerals in FIG. 3 refer to the following matters:

T-die molten web solvent cooling water sealing cover having also a roleas a solvent-separating plate 8 solvent-feeding pipe 9 coolingwater-feeding pipe 11 pinch roll 13 treated film 16 coolingwater-discharging pipe 17 guide roll 18 vessel of cooling water A highdensity polyethylene having a melt index of 0.5 at 190 C. and a densityof 0.955 was melt-extruded from a T-die 1 at 170 C. by means of a usualextruder. The extruded film was introduced into a cooling water 4floating thereupon a solvent layer of n-hexane 3 at 20 C. in a thicknessof 0.5 mm. The surface of the solvent layer was located 30 mm. below thelower end of the die lip and being continuously fed through asolvent-feeding pipe 8. Thus, the film was cooled and solidified. Thesolidified film was then taken up by means of pinch rolls 11 having thenip at a position located 150 mm. below the surface of solvent, at atake-up speed of 10 m./min., via a guide roll 17 to give a treated film13. n-Hexane remaining on the surfaces of film was then removed byevaporation. Thus, Sample No. 8 having both the surfaces roughened wasobtained. Sample No. 9 having both the surfaces roughened was obtainedin a similar manner except that n-propyl acetate was substituted forn-hexane.

Further, Sample No. 10 was obtained similarly but without using anysolvent. The properties of these Samples are shown in the followingTable.

Sample Nos. 8 and 9 prepared according to the present invention were matand opaque, and had a white and paper-like appearance, whereas No. 10was a translucent film having fiat and smooth and considerably lustrousEXAMPLE Example 4 was repeated except that a medium density polyethylenehaving a melt index of 0.5 at 190 C. and a density of 0.935 wassubstituted for high density polyethylene and n-propyl acetate wassubstituted for n-hexane. Thus, Sample No. 11 was obtained. Further,Sample No. 12 was obtained similarly but without using any solvent.

No. 11 prepared according to the present invention was white and opaqueand had mat and roughened surfaces and a paper-like appearance.

EXAMPLE 6 An experiment was carried out using an apparatus as shown inFIG. 4. The numerals shown in FIG. 4 refer to the following matters:

1 monofiament die 2 molten filaments 3 solvent 8 solvent-feeding pipe 11pinch roll 13 treated filament 17 guide roll 20 solvent-discharging pipe21 vessel of solvent 22 separating plate for sealing A polypropylenehaving an intrinsic viscosity of 1.40 and an isotactic index of 96% wasextruded from a monofilament die 1 (12 filaments) at 250 C. by means ofa usual extruder. The extruded molten filaments 2 were led into a layerof a solvent of n-heptane having the surface at a position 100 mm. belowthe lower end of the die and maintained at a constant liquid level andat a constant temperature of 60 C. by means of a solvent-feeding pipe 8and a solvent-discharging pipe 20, to give cooled and solidifiedfilaments. Resultant filaments were taken up via a guide roll 17 locatedmm. below the surface of liquid, by means of pinch rolls 11, at atake-up speed of 5 m./min., while the attached solvent was squeezedthere, whereby treated filaments 13 were obtained. After drying by hotair, Sample No. 13 having a roughened surface was obtained. Theimmersion distance of the filaments in the solvent in this case was 400mm.

The above-mentioned procedure was repeated except that water at 60 C.was substituted for n-heptane. Thus, Sample No. 14 having non-roughenedsurface was obtained. Further, Sample No. 13 was stretched to 5 timesthe original length in a vessel of hot water at 98 C. to give Sample No.15. The appearances of these Samples are shown in the following Table:

Sample Diameter No. (mm.) Appearance 13.-... 1. 2 Mat, roughenedsurface, white, opaque.

14., 1. 0 Lustrous, flat and smooth surface, transparent. 15 0. 7 Mat,roughened surface, white, opaque.

The experiment of this Example was carried out in a similar manner toExample 6, using the same apparatus as in Example 6, but a high densitypolyethylene having a melt index of 3.0 at C. and a density of 0.955 wassubstituted for polypropylene. The polyethylene was melt-extruded from amonofilament die at 230 C., and then led into 1,1,l-trlchloroethanemaintained at 60 C., where the filaments were cooled and solidified.After taking up at a speed of 20 m./min., the treated filaments weredried by hot air to give surface-roughened Sample No. 16. Theabove-mentioned procedure was repeated except that cyclohexane,tetrahydrofurane, and water at 60 C. were substituted for1,1,1-trichloroethane, whereby Sample Nos. 17 and 18 having roughenedsurface and Sample No. 19 having no roughened surface were obtained.Further, No. 16 was stretched to 5 times the original length in a vesselof hot water at 98 C. to give Sample 'No. 20. Sample Nos. 16, 17, 18 and20 prepared according to the present invention had a remarkably rough-3, 322,333 11 12 ened surface as seen in the following Table, whereasNo. EXAMPLE 11 19 had no roughened Surface: Sample No. 2 of Example 1and Sample No. 10 of Example 4 were each boiled in the respectivesolvents as Sample Diameter A shown in the following Table, atrespective boiling temper- No. (mm.) ppea anc 5 ature, for minutes andin a ratio of solvent to resin Matyroughened surfacawhitaopaque of10021. The solvent remaining on the surface of film 17 1.2 Do.

Was removed by air-drying. The properties of the SamplesLustrousrfifltand moth translucent thus obtained are shown in thefollowing Table. In spite 20 0.7 Mat, roughened surface, white, opaque.

of the boiling of these Samples, only a very small amount 10 of anatactic portion or a lower molecular weight por- EXAMPLE 8 tion wasextracted and no dissolution phenomenon of isotactic portion took place.Further, there was almost no Example 1 was repeated that n'pFmaneacyclo' change in the flatness, smoothness and lustre of the sur- Pn-pl'opylchlorlde and l'butylchlonde were face. Thus, the mat, opacityand whiteness due to the stituted for n-hexane- Thus, Sample 23 and 15surface-roughening which are the specific features of the 24 wererespectively obtained. Any of these was a white treatment of the presentinvention, were not observed and opaque film having a mat and roughenedsurface. at all.

Reduction Boning Original in weight Lustre 3 point sample Resin Solvent(percent) (percent) Appearance C.)

2 PP n-Pentane 0.7 2 PP n-Hexane 1.2 2 PP n-Heptane 1.9 2 PPCyclopentane 1.0 2 PP n-Propylchloride 0.9 2 PP i-Butylchloride 1.1

Flat, smooth and considerably lustrous surface,

translucent 10 3 10 69 49 41 10 68 l i l ii t l thylene 1 1 ensi 0 ye l'i helustres of sampl s iqo. 2 and 29-34 are those of the outer surfaceof tube.

EXAMPLE 9 EXAMPLE 12 Example 4 was repeated except that n-pentane,cyclopentane, n-propylchloride and i-butylchloride were substituted forn-hexane. Thus, Sample Nos. 25, 26, 27 grid 40 28 were respectivelyobtained. Any of these was a w rte minutes in an oven maintained at agiven temperature. and opaque film having a mat and roughened SurfaceImmediately after taken out, they, together with the alu- EXAMPLE l0minum foil, were immersed and cooled for 10 minutes in to uene orn-hexane at 20 C. The tern erature ris of th Offset pnntmgf g i 3: 3 gggif g 2: solvent during the period was 1 C. or fess. After :ooling 2:: gg g 223g; gfi It was found g thefsheets were taken out. The solventremaining on the sur ac ofth compared with conventional art paper, tlileml;1 setting was g he: air a: 2 62 ::er:;;oe: ;rbc3;:i$p:l 5: 1; z b zfz ge so rapid in the case of Sample No. 1 t at t ere was no be n1transfer of ink from the printed surface even immediately a1 g and aftersolvent treatment are Shown in the aft ting and the anchoring of ink wasalso sufficient following Table er Prm As a ar t f On the other hand,printing was impossible upon the pp en mm the Table when Polyolefinresms 1n surface of Sample No 2 because ink setting was so slow 'i butpreformed state heated to above their meltv I I that ink transferoccurred so remarkably and anchoring mg P Were quenched and solidifiedby contacting with a solvent mat whiteness and opacity due to remarkkwas extremel bad. Further, a good quality paper r,- 3 g v i iig athickness 0 2 was applied to the surface of do able surfaceroughenmgwere Obtalned In either case of Sample 1 with Starch paste followed bydrying The toluene or n-hexane. On the other hand, in the case ofPress-shaped sheets composed of the resins as shown in the followingTable and having a thickness of 2 mm. were each put on a thin aluminumfoil and heated for 10 resulting product had a peeling strength close tothat of Polyolefin resms not 111 a molten State, ellell o gh they aproduct Obtained by applying a good quality paper to were heated to atemperature close to their melting points each other. On the other hand,with Sample No. 2, such 60 and allowing thermal deformation to occur,the abovean anchoring was not possible at all. mentioned elfctivenessescould not be obtained at all.

Melting Heating Appearance of sheet point temp. Resin 0.) 0.) Beforeheating After solvent-treatment 1 170 Flat, smooth and lustrous Flat,smooth and lustrous surface similar to that before heating, trans- P]?of Example 1 1 175 surface, translucent. lucent.

0 Mat and white surface due to remarkable surface-roughening, opaque.

18 130 Flat, smooth and lustrous Flat, smooth and lustrous surfacesimilar to that before heating, a

surface having a milky milky white feeling, almost opaque. 140 whitefeeling, almost Mat and white surface due to remarkablesurface-toughening, opaque.

o a ue. }F1ats?no0th and lustrous {Flag smooth and lustrous surfacesimilar to that before heating, transsurface, translucent. lucent. I

Mat and white surface due to remarkable surface-rougheniug, opaque.

HDPE of Example 4 135 MDPE of Example 5 1 Among the solvent-treatedsurfaces, the surface which was not brought in contact with aluminumfoil was observed. 1 P P =polypropylene.

8 HDPE=high density polyethylene.

I MDPE=medium density polyethylene.

13 What is claimed is: 1. A process for producing shaped articles ofcrystalline polyolefin resins having a roughened surface which comprises'(a) maintaining a reservoir of a liquid solvent, (b) maintaining asupply of molten polyolefin resin, withdrawing molten polyolefin resinfrom said supply and extruding the withdrawn molten resin into a moltenmass that has a thicknes sof 1 mm. or less,

(d) immediately thereafter, introducing the thus meltextruded polyolefinresin, while it is still in the form of a molten mass, into saidreservoir of liquid sol vent to first cool and solidify the surface andthereafter cool the interior of the mass of the polyolefin resin, thecooling and solidification of the surface of the resin being completedwithin the span of between several tenths of a second and severalseconds and the cooling and solidification of the entire mass ofcrystalline polyolefin resin being completed in one minute or less, saidroughening taking place after the resin is introduced as a melt into thesolvent and before removing the resin from contact with the solvent,

(e) removing said cooled and solidified polyolefin resin from saidreservoir of liquid solvent and recovering a shaped article ofcrystalline polyolefin resin having a roughened surface.

(f) said liquid solvent (1) being selected from the group consisting ofaliphatic, aromatic, alicylic or halogenated hydrocarbons, heterocycliccompounds, and esters of aliphatic alcohols and aliphatic or aromaticcarboxylic acids,

('2) having a boiling point of 30-400 C., and

i(3) does not dissolve said crystalline polyolefin resin in an amount ofby weight or more at a temperature in the range lower than the boilingpoint of said solvent,

(g) said reservoir of liquid solvent being maintained at a temperaturewhich is both (1) within the range of about 0-100 C., and

(2) below the boiling point of the solvent, and

(3) below the temperature of said melt-extrudate 2. A process accordingto claim 1 wherein said reservoir of liquid solvent is floated upon areservoir of a non-solvent cooling liquid which forms a separate phasefrom said solvent and being maintained at a temperature which is equalto or lower than said temperature of solvent, said solvent reservoirfloated upon said cooling liquid, having a thickness of 0:5 mm. or more.

3. A process according to claim 2 wherein said cooling liquid is water.

4. A process according to claim 1 wherein said resin is crystallinepolypropylene and the temperature of said solvent is in the range of0-70 C.

5. A process according to claim 1 wherein said resin is high densitypolyethylene and the temperature of said solvent is in the range of0-'60 C.

6. A process according to claim 1 wherein said solvent is an aliphaticor alicyclic hydrocarbon having a boiling point of 30-'100 C.

7. A process according to claim 1 wherein said solvent is selected fromthe group consisting of pentane, hexane, heptane, octane, nonane,decane, gasoline, petroleum ether, petroleum benzine, ligroin, kerosene,gas oil, liquid paraffin; benzene, toluene, xylene; cyclopentane,cyclohexane, methylcyclohexane, cycloheptane, decahydronaphthalene,tetrahydronaphthalene; tetrahydrofuran; monochloropropane,monochlorobutane, monochloropentane, trichloroethane, tetrachloroethane,trichloroethylene, tetrachloroethylene; propyl acetate, butyl acetate,amyl acetate, dioctyl adipate, dioctyl sebacate and dioctyl phthtalate.

References Cited UNITED STATES PATENTS 3,155,754 11/1964 Adams 264-3433,179,484 4/ 1965 Tessandori 264343 2,979,774 4/ 1961 Rusignolo 264343ROBERT F. WHITE, Primary Examiner G. AUVILLE, Assistant Examiner US. Cl.X.R.

